The Detection of Central Nervous System Tissue on Beef Carcasses and in Comminuted Beef

Abstract

We report the development and validation of a fluorescent enzyme-linked immunosorbent assay (ELISA) for glial fibrillary acidic protein (GFAP), which can be used as a rapid and sensitive method to detect CNS tissue in meat products. The fluorometric assay is sensitive to 0.2 ng GFAP and has an intra-assay coefficient of variation (CV) of 2.0% and an interassay CV of 14.1%. Bovine spinal cord and brain demonstrate dose-response curves that are parallel to GFAP standards, whereas peripheral sciatic nerve and cervical ganglia also cross-react at high tissue levels. The use of another central nervous system marker, syntaxin 1-B, was not effective for neural tissue detection. Less than 1.0 ng GFAP per mg tissue was found on most beef subprimals and advanced meat recovery (AMR) product. Occasional samples contained higher levels of GFAP, probably because of contamination by the carcass-splitting saw, incomplete removal of the spinal cord, or a chance sampling of a major nerve. Further reduction of CNS content was facilitated by removal of the cervical vertebrae and the spinal canal prior to processing beef chuck bones through AMR equipment. The presence of GFAP was very low (0.037 ng/mg) in beef patties collected from major processors throughout the USA. The presence of normal sausage ingredients or heating the product to 80°C for 60 min did not affect the detection of GFAP. Heating the product to 115°C for 100 min eliminated the detectability of GFAP.